1. Field of the Invention
This invention relates to pullers, in particular to compression sleeve pullers having a duality of screw thread engagement and includes method of manufacture.
2. Description of Prior Art
A pipe which contains pressurized fluid may be connected to a valve which is used to dispense the pressurized fluid in a controlled manner. An example is household plumbing lines bringing water into the premises. The individual branches of the plumbing system are routed inside the walls of the house and terminate inside a room such as a bathroom or kitchen. The plumbing lines protrude through the wall far enough to attach a water valve. A common method of attaching and sealing a water valve to a plumbing line is to employ the use of a compression fitting consisting of a compression nut, a compression sleeve and the valve. To install the valve, (1) the compression nut is placed on the pipe; (2) the closely fitting compression sleeve is slipped onto the pipe; and (3) the valve is pushed on and engaged with the compression nut. The nut is then tightened onto the valve to compress the compression sleeve onto the pipe. The compression sleeve creates both a mechanical grip for the valve and a pressure seal for the fluid. Other methods of attaching the valve include: (a) threading the valve into a threaded pipe fitting and sealing the point of attachment with pipe sealant; or (b) soldering the valve to the pipe. When a valve wears out or fails, it must be removed and replaced. This invention applies only to the removal of valves which are attached using the compression sleeve method of attaching and sealing.
When replacing a valve or other device attached to a pressurized pipe by means of a compression sleeve fitting, it is important to remove the old compression sleeve and replace it with a new compression sleeve to ensure proper sealing. Generally, plumbing pipe comprises thin wall copper tubing. This tubing is easily damaged when old compression sleeves are reused because the old sleeve generally must be over-tightened to obtain a seal.
The removal of the old compression sleeve requires specially designed tooling to pull the old sleeve off the copper pipe without damage to the pipe. If the pipe is dented, scratched or deformed, it is generally impossible to reseal with a compression sleeve. This results in the need to replace the damaged pipe or otherwise causes extra work and expense.
Compression nuts used for this application come in two standard thread designs: coarse thread and fine thread. Although both thread designs possess the same inner diameter, two puller tools are required to couple with the differing thread designs. In lieu of two tools, the prior art discloses a single tool which incorporates a removable adapter to change from the coarse thread to the fine thread or vice versa. This type of puller is shown in U.S. Pat. No. 5,519,929 issued to Bleckman. Bleckman discloses a removable threaded adapter which threads to the end of the body of the tool to provide coupling to the alternate thread design. For example, if the tool is manufactured with the fine thread design at the coupling end, then the adapter is manufactured with a fine inner thread, a stepped down inner portion to match the inner diameter of the tool body, a hexagonal or knurled outer diameter for aid in threading it to the tool body, and a coarse outer thread to mate with the compression nut to be removed. This adapter represents 50% of the utility of the tool and approximately 30% of the total cost of the tool.
The required adapter is easily lost or misplaced. Moreover, the adapter is difficult to find in a plumber's toolbox because of its diminutive size. Also, the use of the adapter increases the length of the tool thereby decreasing its usefulness. Bleckman points out that the longer the tool, the more difficult it is to use in the normal plumbing environment of tight quarters and adjacent obstacles such as pipes, sinks and walls. The disadvantages of the additional removable adapter are significant enough to make the tool as a whole less desirable to both the professional plumber and the handyman.
The Bleckman design also discloses an unnecessarily complex and costly bearing device/alignment plug consisting of a larger diameter cylindrical bearing device stepped down to a smaller diameter, tapered, alignment plug used to center the bearing device to the edge of the pipe. Alignment is necessary to prevent the larger diameter bearing device from catching on the compression sleeve as it passes through. The complexity of the bearing device/alignment plug adds unnecessary cost and size to the tool. It has been discovered that if the tapered alignment plug is eliminated and the cylindrical bearing device is replaced by a relatively thin, loose fitting, rotatable disk, the tool operates perfectly well without the additional alignment plug. It was found that the when the disk encounters the compression ring, it self-centers and passes through with no difficulty. The simple disk comprises only about 2% of the cost of the tool whereas the complex bearing device/alignment plug disclosed by Bleckman comprises about 15% of the cost of that tool. Therefore, by eliminating the adapter and replacing the bearing device/alignment plug with a simple disk, the cost of the tool is reduced by about 43%.
The Bleckman design suffers from the following disadvantages:                (a) the separate adapter which is necessary for the tool to be used for both fine and course compression nuts is expensive;        (b) the separate adapter adds undesirable length to the tool;        (c) the separate adapter is easily lost or misplaced;        (d) the bearing device/centering plug is overly complex and expensive.        
Therefore, there is a need for a less complex and costly tool which couples to both fine and coarse threaded compression nuts without the use of an undesirable adapter and operates smoothly without the need for a complicated bearing device/centering plug.
3. Summary of the Invention
The present invention is a dual thread design compression sleeve puller which fits both coarse and fine threads without the use of an additional adapter. The two threads, coarse and fine, are both cut in the threaded end of the tool so that the tool automatically fits either thread on the compression nut. This overcomes the disadvantages of the thread adapter necessary for prior art and makes the tool more productive and less expensive. It also eliminates the possibility of loss of the adapter. The present invention also elimates the bearing device/centering plug and replaces it with a simple disk which functions for both purposes.
4. Objects and Advantages
It is therefore an object of the present invention to provide a new and useful compression sleeve puller with a double thread engagement. Further objects and advantages of the present invention are as follows:                (a) to provide a puller which threadably couples to compression nuts of either fine or coarse thread design without the use of an adapter;        (b) to provide a tool which does not require the use of an alignment plug for centering on the pipe;        (c) to provide a puller of simple design which is easy to use in tight quarters;        (d) to provide a puller which is durable enough for the professional and inexpensive enough for the handyman or homeowner;        (e) to provide a puller which is easy to attach to the compression nut without the use of tools and supports itself when so attached;        (f) to provide a puller which can be operated simply, quickly and in most cases with one hand;        (g) to provide a puller which can be attached and operated by a person with average skill and strength,        (h) to provide a puller which reduces the time and effort for the removal of compression sleeves and increases productivity; and        (i) to provide a method of manufacture which will overcome the limitations and disadvantages of threaded pullers heretofore provided.        